Oxidation of butane to make anhydride and catalyst therefor

ABSTRACT

A catalyst comprising Sb-Ni-Mo has been found to be very selective, stable and long-lasting in the conversion of butane to maleic anhydride. Other metals such as Co, Cu, or Zn may be substituted for Ni with like results. An improved method for preparing this catalyst is also provided herein.

United States Patent [191 Cherry et al. 5] Dec. 23, 1975 OXIDATION OF BUTANE TO MAKE [56] References Cited ANHYDRIDE AND CATALYST THEREFOR FOREIGN PATENTS OR APPLICATIONS Inventors: Wesley y, Prospect Park; 2,072,336 9/1971 France 260/346.8

Alan F. Dickason, Chester, both of P36 him Hedge wllmmgton, Primary Examiner-Harry I. Moatz Attorney, Agent, or Firm-George L. Church; Donald [73] Assignee: Sun Ventures, Inc., St. Davids, Pa. Johnson; Stanford Back 22 Fl (1: Oct. 17 1973 21 A N 407 346 [57] ABS CT 1 pp A catalyst comprising SbNiMo has been found to be very selective, stable and long-lasting in the conver- Cl 6 /3463 A; 252/468; 252/467; sion of butane t0 maleic anhydride. Other metals such 252/470 as Co, Cu, or Zn may be substituted for Ni with like [51] Int. Cl. C07D 307/56 results An improved method for preparing this cata- [58] Field of Search 260/346.8; 252/467, 468, lyst is also provided herein.

9 Claims, No Drawings OXIDATION OF BUTANE TO MAKE ANIIYDRIDE AND CATALYST THEREFOR BACKGROUND OF THE INVENTION This invention relates to a novel method for the catalytic vapor phase oxidation of butane with oxygen or air to form maleic anhydride wherein there is employed as the catalyst system an oxide composition containing antimony, molybdenum, and a third metal selected from the group consisting of Ni, Co, Cu, and Zn. This invention also relates to a novel method for preparing this catalyst.

The vapor phase oxidation of butane to maleic anhydride using various combinations of metals, metal oxides and/or metal salts as catalysts is well known in the art as shown, for example, in U.S. Pat. Nos. 2,625,519 and 2,691,660 (e.g., Co/Mo); U.S. Pat. No. 3,074,969 (e.g., V-Mo-alkali metal chloride); U.S. Pat. No. 3,293,268 (e.g., VIP) and U.S. Pat. No. 3,055,842 (e.g., V/Ti/Mo/Al), as well as Belgian Pat. No. 771,795 teaching the use of a four-component vanadium-containing catalyst.

SUMMARY OF THE INVENTION In accordance with the present invention, it has now been found that an oxide composition containing antimony, molybdenum, and a third metal selected from the group consisting of nickel, cobalt, copper, and zinc, provides an effective catalyst for the vapor phase oxidation of butane to maleic anhydride. This catalyst is characterized in particular by its stable level of selectivity at high conversion.

PREPARATION OF THE CATALYST The catalysts of this invention may conveniently be prepared in a manner similar to the teachings of Canadian Pat. No. 796,787 or U.S. Pat. Nos. 3,595,910 and 3,595,91 l Thus, for example, in accordance with these methods, an Sb/Ni/Mo catalyst may be prepared as follows: antimony pentachloride is added to a solution of nickel chloride hexahydrate in water, and the pH of the mixture adjusted to 6.5 with ammonia. The resulting precipitate, after washing, is then mixed with a solution of ammonium molybdate, the mixture dried, the dried cake ground up and calcined in oxygen or air at temperatures of from about 600 900C for several hours, principally at about 700C.

The resulting catalyst is characterized in being roughly mottled yellow-green in color, and is further characterized in providing selectivities for the desired maleic anhydride in the range of about 25 to 30 percent. lnasmuch as the color characteristics of this catalyst are subject to change, this quality cannot be considered to be a fully established one.

Alternatively, the Sb/Ni/Mo catalyst may be prepared by a somewhat different method which, compared with the above method, advantageously permits substantial control of the quantity of the third metal which is incorporated in the Sb/Mo composition. The first method permits little, if any, latitude in this respect. The catalyst prepared by this alternative method also provides higher selectivities over a longer period of time. When nickel, for example, is employed, the resulting Sb/Ni/Mo catalyst is characterized by providing selectivities of about 25-35 percent. The catalyst is further characterized by a uniform greenish-brown color, but again it will be understood that this color characteristic is not necessarily a fixed one. However, although the applicants do not wish to be bound by any particular theories, it is believed that the yellowish color of the first catalyst represents a partially activated form which provides lower selectivities than does the greenish-brown form. The second catalyst, which is more greenish in color, is therefore, believed to represent a catalyst which is more uniform in composition and properties with respect to selectivity in converting butane to maleic anhydride. Again, while not wishing to be bound by any particular theory, it is believed that the properties of the more uniform catalyst are a result of the temperatures at which it is calcined, i.e., at temperatures of over 7 50C and preferably at temperatures of at least 800C, as described below, and in Example 14.

This alternative form of catalyst may be prepared using, for example, nickel as the third metal, by first dissolving a watersoluble antimony salt such as SbCl in water in amount of preferably about 20-25% by weight, preferably at temperatures below 35C, warming the solution to room temperature, adjusting the pH of the resulting solution with a suitable alkaline reagent such as NH OH to about pH 6.5, thereby precipitating said salt, and filtering, washing and drying the resulting precipitate to a moist cake. To this material is then added an aqueous solution of a water-soluble molybdenum salt and nickel salt such as ammonium molybdate and nickel nitrate in amounts of about 5-15% and about 15-25% by weight, respectively. The resulting composition, after evaporation, is dried at about 1 10 to 130C for about 15 to 20 hours, crushed to small particle size and calcined at a temperature of from about 750C to 850C, and preferably about 800C for about at least 2 hours, preferably about 3 to 6 hours. It will be understood that in a like manner other Sb/Mo catalyst, where the nickel is substituted by cobalt, or the like, may be prepared by employing salts such as cobalt nitrate, copper chloride, or zinc chloride, as shown, e.g., in U.S. Pat. Nos. 3,595,910 or 3,595,911 (supra).

Analysis of these catalysts reveal that the percentage range of antimony present is about 40 to atomic percent based on the total metals present, and preferably is about 72 to 81 atomic percent. The corresponding atomic percent of nickel and molybdenum is desirably in the range of 5 to 40 percent for nickel, preferably about 8 to 18 percent, and l to 20 percent for the molybdenum, preferably 6 to 15 percent, respectively, based on the total metals of the composition. When other metals are substituted for nickel the same general ratios still prevail.-

Surprisingly, it has been found that these catalysts are most effective when they are not supported on any inert carrier. That is to say, the presence of a support substantially reduces, or on occasion, nullifies the activity of the catalyst, and it should, therefore, desirably be used alone.

As aforestated, the Sb/Ni/Mo catalysts of this invention may be modified by substituting for the nickel component a metal selected from the group consisting of cobalt, copper, or zinc. This may readily be achieved by simply employing the salts enumerated above, or like soluble salts in place of the nickel chloride compound. Otherwise, the process for preparing the catalyst remains as described above.

OF BUTANE TO MALEIC ANI-IYDRIDE The vapor phase oxidation of butane to maleic anhydride, using the aforedescribed catalysts, may conveniently be carried out by passing the butane, together with oxygen and/or air over a bed of said catalyst at temperatures of from about 350 to 650C, and preferably about 400 to 500C, at contact times of from about 0.001 sec. to sec., and preferably about 0.1 to 2 sec., and at pressures ranging from atmospheric pressure to about 100 lbs./in.2, where the catalyst bed may be either a fixed bed, a fluidized bed, or a moving bed. The concentration of oxygen in the feed stream may vary within moderately wide limits but should desirably be from about 1 to 20 percent by volume of the total feed stream, and preferably about to percent, while the volume of butane contained in the feed should desirably be from about 0.1 to 10 percent and preferably 1 to 5 percent. It will be understood that the oxygen may be diluted with inert gases, or supplied as air.

The maleic anhydride may be recovered from the reaction product by any conventional method, for example, by passing the effuent through water, then stripping of the water. The catalyst may, when necessary, be readily regenerated by treating it with air or oxygen at temperatures up to 700C.

This invention will now be illustrated by the following examples.

OXIDATION CATALYST PREPARATIONS EXAMPLE 1 Antimony: Nickel: Molybdenum Catalyst Antimony pentachloride (SbCl 149.5 g.) was added slowly to a stirred solution of nickel chloride hexahydrate (NiC1 6l-1 O, 1 18.9 g) in 500 milliliters of distilled water. (The temperature increased from 28C to 42C). The'pI-I of the mixture was adjusted to 6.5 with concentrated aqueous ammonia using an ice bath to keep the temperature below 60C. The mixture was then stirred for 45 minutes, filtered, the filter cake washed three times by resuspension in 500 milliliter portions of distilled water and filtered again.

The moist filter cake was then mixed with ammonium molybdate (NI-I Mo O .4H O, 1.1 g.] in 100 milliliters of distilled water, evaporated to a thick paste on a steam bath, and dried at 110-120C for 16 hours. The dried cake was broken to pass a 4 mesh screen and calcined from to 700C over 8 hours, then held at 700725C for 16 hours.

EXAMPLE 2 Antimony: Nickel: Molybdenum Catalyst Antimony pentachloride (SbCl 25 g) was added slowly to distilled water (250 mls.) with stirring. The temperature of the suspension was maintained below 35C with an ice bath. The suspension was allowed to warm to room temperature, then the pH was adjusted to 6.5 with concentrated aqueous ammonia (about 85 ml) while stirring for 45 minutes. The precipitate was filtered, washed three times with 250 milliliters of distilled water for 15 minutes and filtered again.

Ammonium molybdate [(NH MQ O ,.4H O, 2.2 g] was dissolved in distilled water (40 ml.) at room temperature. Nickel nitrate hexahydrate [Ni(NO .6I-I O,

4 2.8 g] was dissolved in distilled water 10 ml.) at room temperature and then combined with the ammonium molybdate solution.

The combined solution was then added to the moist filter cake and stirred. The mixture was then evaporated to a thick paste while stirring on a steam bath. The paste was dried at 110 to 120C for 16 hours. The dried cake was crushed to pass a 4-mesh screen and the resulting particles calcined at 800C for 3 hours.

This procedure was used to prepare catalysts with varying ratios of the three components by changing the concentration of the ammonium molybdate and the nickel nitrate solution.

EXAMPLE 3 Antimony: Cobalt: Molybdenum Catalyst Antimony pentachloride (SbCl 149.5 g) was added slowly to a stirred solution of cobalt chloride hexahydrate (CoCl .6I-I O, 42.5 g.) in 500 milliliters of distilled water. The pH of the mixture was adjusted to 7.0 with concentrated aqueous ammonia using an ice bath to keep the temperature below 60C. The mixture was stirred for 45 minutes, filtered and the filter cake washed three times by resuspension in 500 milliliter portions of distilled water. The filter cake was dried for 16 hours at 110 to 120C and crushed to pass a mesh screen.

The 100 mesh powder was then mixed with ammonium molybdate [(NI-I Mo7O .4H O, 11.1 g] in 100 milliliters of distilled water and evaporated to a thick paste on a steam bath. The catalyst was dried at 1 10 to 120C for 16 hours crushed to pass a 4-mesh screen, and calcined from 25 to 700C for 8 hours, then held at 700725C for 16 hours.

EXAMPLE 4 Antimony: Copper: Molybdenum Catalyst Antimony pentachloride (SbCl 149.5 g) was added slowly to a stirred solution of copper chloride (CuCl 16.8 g) in 500 milliliters of distilled water. (The temperature increased from 28C to 42C). The pH of the mixture was adjusted to 6.5 with concentrated aqueous ammonia using an ice bath to keep the temperature below 60C. The mixture was stirred for 45 minutes, filtered, the filter cake washed three times by resuspension in 500 milliliter portions of distilled water and filtered again.

The moist filter cake was then mixed with ammonium molybdate [(NH Mo O .4l-1 O, 11.1 g] in 100 milliliters of distilled water, evaporated to a thick paste on a steam bath and dried at to C for 16 hours. The dried cake was broken to pass a 4 mesh screen and calcined from 25 to 700C over 8 hours, then held at 700725C for 16 hours.

EXAMPLE 5 Antimony: Zinc: Molybdenum Catalyst Zinc powder (16.4 g) was dissolved in concentrated hydrochloric acid (177 g) keeping the temperature at about 30C with an ice bath. Antimony pentachloride (SbCl 128 g) was added slowly to the zinc chloride solution. The pH was adjusted to 7.0 by the slow addition of aqueous ammonia, maintaining the temperature below 60C in an ice bath. The mixture was stirred for 45 minutes, filtered, the filter cake washed three times by resuspension in 500 milliliter portions of distilled of an antimony-nickel-rnolybdenum catalyst (prepared water and filtered again. 4 1 v I as described inExarnple] contained in a inch X 2% The moist filter cake was then mixed with? ain'ni ohium feet stainless steel reactor. The contact time was 0.46 molybdate [(N1-1 Mo-,O .41-l O, 44.2 g] inl"l rnilli sec. at 402C. The selectivity to maleic anhydride was liters of distilled water, evaporated to a thick paste on 30% at 36% conversion of butane. a steam bath and dried at 1 to 120C for 16 hours; A unique feature of this catalyst is the constant selec- The dried cake was broken to passa 4"rnesh screen and tivity with increase in conversion as shown by the data calcined from 25 to 700C over 8' hours, then heldat in Table 1.

700-725C for 16 hours.

)g T 10 TABLEI EXAMPLEb I e CONTACT TIME-TEMPERATURE sTupY FOR THE Cobalt/Molybdenum Catalyst OXIDATION OF BUTANE OVER AN Sb/Nl/Mo CWATALYST Molybdenum trioxide (M00 ,72 g) was slowly E isfg Con rsion Yi e ld added to concentrated aqueous ammonia (140 mls.)

then diluted to 500 milliliters with distilled water. The

1 2 mixture was stirred until all the molybdenum trioxide 3 400 58 27 16 dissolved and then diluted to two liters with distilled g 83; 8 83% g? i? water. Boric acid (50 g.) was added to buffer the solug 8.22 8 8.; :55; 53 T3 tion and the temperature was increased to 95C.

Cobalt nitrate [Co(NO .61-1 O, 87.4 g] was dis- 20 g 0'54 453 023 70 26 18 solved in 200 milliliters of distilled water and heated to 90C. The hot cobalt nitrate solution was poured into the stirring molybdenum solution forming a blue precipitate. The precipitate was filtered hot and the filter EXAMPLE 9 cake air dried for one hour with tamping. The filter Oxidation of Butane with Antimony: Nickel: cake was dried for 16 hours at ll0-l20C, then Molybdenum Catalyst crushed to pass a 4-mesh sieve. The 4-mesh particles A gaseous mixture of butane (1 10 mole and air were calcined in a tube with flowing air for 3.5 hours at (98 90 mole was passed Over 1150.44 g of an 350 i 30 Sb/Ni/Mo catalyst prepared (as described in Example XAMPL 7 2) contained in a 6 inch X 1/4 inch stainless steel reactor. The contact time was 0.29 sec. at 450C. The selec- Nlckel Molybdate Catalyst tivity to maleic anhydride was 33 moles at 27% con- Molybderium trioxide (M00 72 g) was slowly version. added to nickel nitrate hexahydrate [Ni(NO .6H O, 35 The effect of varying the ratio of SbzNizMo (i.e., Sb 145.5 g] then diluted to 300 milliliters with distilled held constant (1.0) while NizMo varied) is shown in water. The mixture was stirred until all the molybde- Table 1V.

TABLE 11 Run (Sb 1.0) Reaction Time(T) No. Cale. Anal. Temp.,C (Sec) Conv. Sel.

num trioxide dissolved and then diluted to 2 liters with EXAMPLE l0 distilled water. Bor1c acid g.) was added to buffer 50 Oxidation of Butane with Antimony; cobalt: glise csolution and the temperature was increased to Molybdenum Catalyst A gaseous mixture of butane (0.60 mole and air (99.40 mole was passed over 23 mls (44.3 g) of an antimony: cobalti molybdenum catalyst (prepared as 5 described in Example 3) contained in a inch X 2% feet stainless steel reactor. The contact time was 0.81 sec. at 400C. The selectivity to maleic anhydride was 34 mole at 57% conversion.

Several additional runs were carried out with this 6 catalyst to show that the selectivity was relatively constant up to at least 74% conversion. The data are shown Cobalt nitrate (Co(NO .6H O, 87.4 g) was dissolved in 200 milliliters of distilled water and heated to C. The hot cobalt nitrate solution was poured into the stirring molybdenum solution forming a blueprecipitate. The precipitate was filtered hot and the filter cake air dried for 1 hour with tamping. The filter cake was dried for 16 hours at] 10 to C then crushed to pass a 4-mesh sieve. The 4-mesh particles were calcined in a tube with flowing air for 6 hours at 590C.

LII

OXIDATION o BUT NE in the following table:

EXAMPLE 8 TABLE 111 Oxidation of Butane with Sb/Ni/Mo Cataly 65 OXIDATION OF BUTANE To MALElC ANHYDRlDE* (1102420311 atomic Patio i TeJClp- C4 l s l convi rsion Selezfivity A gaseous mixture of butane (0.8 mole percent) and l 403 Q67 38 37 35 air (99.2 mole percent) was passed over 29 g (19 mls) 2 402 0.59 .80 55 33 TABLE III-continued OXIDATION OF BUTANE TO MALEI C ANHYDRIDqE" Run Temp. T1me(T) No. "C C (Sec) Conversion Selectivity using 33 ml (39g) of antimony: cobalt: molybdenum EXAMPLE 1 l Oxidation of Butane with Antimony: Copper: Molybdenum Catalyst A gaseous mixture of butane (0.84 mole and air (99.16 mole was passed over 16 mls. (12.49 grams) of an antimony:copper:molybdenum catalyst (prepared as described in Example 4) contained in a inch X 2% feet stainless steel reactor. The contact time was 0.66 sec. at 425C. The selectivity to maleic anhydride was 40% at 36% conversion.

A second run using butane (0.70%) and air (99.3 mole resulted in 28% selectivity at 77% conversion. The contact time was 0.62 sec. at 502C.

EXAMPLE 13 Oxidation of Butane with Antimony: Zinc: Molybdenum Catalyst A gaseous mixture of butane (0.50 mole and air (99.50 mole was passed over 16 mls. (23.3 grams) of an Sb/Zn/Mo catalyst (prepared as described in Example contained in a inch X 2% feet stainless steel reactor. The contact time was 1.04 sec. at 443C. The selectivity to maleic anhydride was 34% at 24% conversion.

A second runusing butane (1.16 mole and air (98.84 mole resulted in 28% selectivity at 41% conversion. The contact time was 2.08 Sec. at 443C.

EXAMPLE 13 Comparative Runs with Cobalt and Nickel Molybdate Catalysts A gaseous mixture of butane (1.0 mole and air (99 mole was passed over 40.6 g (42 mls) of a cobalt-molybdenum-oxygen catalyst (prepared as described in Example 6) contained in a inch X 2% feet stainless steel reactor. The contact time was 0.94 seconds at 390C. The selectivity was 28% at 29% conversion of butane. Similar runs under varying conditions are shown in Table IV below.

B. Nickel Molybdenum Catalyst A gaseous mixture of butane (0.9 mole and air (99.1 mole was passed over 18.4 (30 mls) of a nickel-molybdenum-oxygen catalyst, (prepared as described in Example 7) contained in a inch X 2% feet stainless steel reactor. The contact time was 0.86 seconds at 506C. The selectivity to maleic anhydride was 29% at 52% conversion of butane. Similar runs under varying conditions are shown in Table V below.

TABLE IV PARAMETER STUDY OF THE OXIDATION OF BUTANE OVER A Co/Mo CATALYST Run C Temp. Sec. Conv. Sel. Yield "Ila" 1D. 8.5. reactor, 18" bed.

TABLE V PARAMETER STUDY OF THE OXIDATION OF BUTANE OVER A Ni/MO Cit/TALYST I 0 0 Run C Temp. Sec. Conv. Sel. Yield EXAMPLE 14 Effect of Calcination Temperatures The following table demonstrates the effect of calcination temperatures on the color and selectivity of certain of catalysts of this invention.

It can be seen from this Table (Table VI) that when the calcination temperature is held at 600C for up to 16 hours, the catalyst possesses activity but there is no selectivity to maleic anhydride. At a temperature of 710C, the calcination time must be held beyond 8 hours before any selectivity is seen. When the calcination temperature is increased to 800 for 3-4 hours, the selectivity increases to 25-33%. However, if the temperature is held at 800 for 8 hours, there is some decrease in the selectivity.

TABLE VI EFFECT OF CALCINATION TIME AND TEMPERATURE ON THE ACTIVITY AND SELECTIVITY OF AN Sb/Ni/Mo CATALYST FOR THE OXIDATION OF BUTANE'TO MALEIC ANHYDRIDE Reaction Calc. Temp. Calc. Time Temperature Run No. C (hrs.) C 1 Conversion Selectivity Comments 1 25-600 7 500 0.47 19 0 Light Yellow 2 600 8 500 0.47 30 0 3 600 16 470 1.40 44 v 0 4 600 16 500 0.24 I, 14 0 5 25-710 8 450 0.30 8 0 6 i 710 8 490 0.32 13 0 Yellow-green 7 710 16 450 0.31 18 11 Light Green 8 0.25 32 30 EFFECT OFCALCINATION TIME AND TEMPERATURE ON THE ACTIVITY AND SELECTIVITY OF AN Sb/Ni/Mo CATALYST FOR THE OXIDATION OF BUTANE TO MALEIC ANHYDRIDE Reaction Calc. Temp. Calc.Time Temperature Run No. C (hrs) "C 1' Conversion Selectivity Comments TABLE VII S ace Time Temp. ime Catalyst C :O (Sec) (C) Conv. Sel. Yield N R Sb/Ni/Mo 1.6:[ 0.20 423 2.4 SI I03 I C BASED C4 02 RATIO 1:20 0.98 400 68 25 30 In a further embodiment of the invention it has been found that when the concentration of butane, relative to the amount of oxygen, is increased in the feed stream, the selectivity for maleic anhydride is likewise increased significantly. Customarily, as in the abovedescribed process, the concentration of hydrocarbon in the feed stream is kept low for safety purposes, i.e., at mol ratios of about 1:4 or lower of hydrocarbon to oxygen, and preferably ratios of 1:10 or lower, e.g. 1:20. Under these conditions, it has been found that the selectivity for maleic anhydride is generally between and 50%.

It has now been found that, contrary to general practice and expectations, when the oxygen is employed as pure oxygen rather than diluted with inert gases, e.g. with nitrogen as in air, and the concentration of butane relative to the oxygen is increased in ratios of greater than 1:4, preferably greater than 1:1, in order to operate outside the explosive limits, the selectivity for maleic anhydride is increased about 20% over what is obtained with a hydrocarbon-lean feed but without any dangerous side effects. Thus, it has been found that ratios of greater than 1:4 may be employed, and preferably ratios in the range of about 1:1 to 20:1 of hydrocarbon to oxygen. Furthermore, a significant increase in space-time-yield is obtained as shown in the following table wherein the space-time-yield increased from to 103 when the CfzO ratio was changed from 1:20 to 1.611 and pure oxygen was employed in place of air.

This feature is of great economic significance when designing a commercial plant. There is an obvious advantage with the higher STY in that the reactor size can be reduced, e.g., in the above case the size could be reduced by a factor of 3.

The following example, which forms part of the subject matter disclosed and claimed in corresponding application, Ser. No. 407,347 filed Oct. 17, 1973, now US. Pat. No. 3,899,516, in the name of Alan F. Dickason, illustrates this improved embodiment of the invention.

EXAMPLE 15 In accordance with the procedures of Example 8, a gaseous mixture of butane (65 mole percent) and oxygen mole percent) was apssed over 2 g of antimony-nickel-molybdenum catalyst (prepared as described in Example 1). The conditions and results obtained are summarized in the following table. For sake of comparison a second run using the conditions described in Table 1 above (Run 4) are also set forth in this table.

The invention claimed is:

l. A process for the vapor phase oxidation of butane to form maleic anhydride which comprises reacting butane with oxygen or air at temperatures of from abut 350 to 650C in the presence of a catalyst composition containing antimony, molybdenum and a third metal selected from the group consisting of nickel, cobalt, copper, and zinc, wherein said catalyst contains at least about 40 atomic percent antimony, less than about 20 atomic percent molybdenum, and less than about 40 atomic percent of said third metal, based on the total metals of the composition, wherein the contact time of the butane with the catalyst is from about 0.001 to 10 seconds, and wherein the mole ratio of butane to oxygen in the feed stream is no greater than 1:4.

2. The process according to claim 1 wherein the catalyst composition contains from about 40 to atomic percent antimony, 6 to 15 atomic percent molybdenum and from about 5 to 40 atomic percent of said third metal.

3. The process according to claim 1 wherein the catalyst composition contains from about 72 to 81 atomic percent antimony, from about 8 to 19 atomic percent nickel and from about 6 to 15 atomic percent molybdenum.

4. The process according to claim 1 wherein the catalyst composition is formed by dissolving an antimony salt in water, adjusting the pH of the solution to about 6.5 to precipitate said salt, adding to said precipitate an aqueous solution of a mixture of a molybdenum salt and a salt of nickel, cobalt, copper or zinc, drying the resulting composition at about 1 10 to C for at least about 15 hours and crushing it to small particle size, and thereafter calcining the particles at atemperature of from about 750 to 850C for at least about 2 hours.

5. The process according to claim 4 wherein the catalyst composition is formed from antimony pentachloride, ammonium molybdate, and nickel nitrate.

6. The process according to claim 1 wherein the oxidation is carried out at temperatures of from about 400 to 500C, and at contact times of from about 0.1 to 2 seconds.

7. The process according to claim 1 wherein the amount of oxygen in the feed is from about 1 to 20 volume percent of the total feed stream.

8. A process for the vapor phase oxidation of butane to form maleic anhydride which comprises reacting 1 1 butane with oxygen or air at a temperature of from about 350 to 650C in the presence of a catalyst composition containing antimony, molybdenum, and a third metal selected from the group consisting of nickel, cobalt, copper, and zinc, said catalyst containing from about 40 to 90 atomic percent antimony, 1 to 20 atomic percent molybdenum, and from about 5 to 40 atomic percent of said third metal, wherein the contact time of the butane with the catalyst is about 0.001 to seconds, and wherein the amount of oxygen in the feed is from about 1 to volume percent based on the total feed stream, and wherein further the mole ratio of butane to oxygen is no greater than 1:4. 

1. A PROCESS FOR THE VAPOR PHASE OXIDATION OF BUTANE TO FORM MALEIC ANHYDRIDE WHICH COMPRISES REACTING BUTANE WITH OXYGEN OR AIR AT TEMPERATURES OF FROM ABOUT 350* TO 650*C IN THE PRESENCE OF A CATALYST COMPOSITION CONTAINING ANTIMONY, MOLYBDENUM AND A THIRD METAL SELECTED FROM THE GROUP CONSISTING OF NICKEL, COBALT, COPPER, AND ZINC, WHEREIN SAID CATALYST CONTAINS AT LEAST ABOUT 40 ATOMIC PERCENT ANTIMONY, LESS THAN ABOUT 20 ATOMIC PERCENT MOLYBDENUM, AND LESS THAN ABOUT 40 ATOMIC PERCENT OF SAID THIRD METAL, BASED ON THE TOTAL METALS OF THE COMPOSITION, WHEREIN THE CONTACT TIME OF THE BUTANE WITH THE CATALYST IS FROM ABOUT 0.001 TO 10 SECONDS, AND WHEREIN THE MOLE RATIO OF BUTANE TO OXYGEN IN THE FEED STREAM IS NO GREATER THAN 1:4.
 2. The process according to claim 1 wherein the catalyst composition contains from about 40 to 90 atomic percent antimony, 6 to 15 atomic percent molybdenum and from about 5 to 40 atomic percent of said third metal.
 3. The process according to claim 1 wherein the catalyst composition contains from about 72 to 81 atomic percent antimony, from about 8 to 19 atomic percent nickel and from about 6 to 15 atomic percent molybdenum.
 4. The process according to claim 1 wherein the catalyst composition is formed bY dissolving an antimony salt in water, adjusting the pH of the solution to about 6.5 to precipitate said salt, adding to said precipitate an aqueous solution of a mixture of a molybdenum salt and a salt of nickel, cobalt, copper or zinc, drying the resulting composition at about 110* to 130*C for at least about 15 hours and crushing it to small particle size, and thereafter calcining the particles at a temperature of from about 750 to 850*C for at least about 2 hours.
 5. The process according to claim 4 wherein the catalyst composition is formed from antimony pentachloride, ammonium molybdate, and nickel nitrate.
 6. The process according to claim 1 wherein the oxidation is carried out at temperatures of from about 400* to 500*C, and at contact times of from about 0.1 to 2 seconds.
 7. The process according to claim 1 wherein the amount of oxygen in the feed is from about 1 to 20 volume percent of the total feed stream.
 8. A process for the vapor phase oxidation of butane to form maleic anhydride which comprises reacting butane with oxygen or air at a temperature of from about 350* to 650*C in the presence of a catalyst composition containing antimony, molybdenum, and a third metal selected from the group consisting of nickel, cobalt, copper, and zinc, said catalyst containing from about 40 to 90 atomic percent antimony, 1 to 20 atomic percent molybdenum, and from about 5 to 40 atomic percent of said third metal, wherein the contact time of the butane with the catalyst is about 0.001 to 10 seconds, and wherein the amount of oxygen in the feed is from about 1 to 20 volume percent based on the total feed stream, and wherein further the mole ratio of butane to oxygen is no greater than 1:4.
 9. The process according to claim 8 wherein said catalyst employed is formed by dissolving an antimony salt in water, adjusting the pH of the solution to about 6.5 to precipitate said salt, adding to said precipitate an aqueous solution of a mixture of a molybdenum salt and a salt of nickel, cobalt, copper or zinc, drying the resulting composition at about 110* to 130*C for at least about 15 hours and crushing it to small particle size, and thereafter calcining the particles at a temperature of from about 750* to 850*C for at least about 2 hours. 